Many humans (and other mammals and animals) receive benefit from implantable medical devices that deliver electrical pulses to or record from desired locations within their bodies. Such medical devices may comprise, for instance, spinal cord stimulation (“SCS”) electrodes which typically comprise a small lead wire that is connected at one end to a power source and at the opposite end to a plurality of electrical contacts configured to transfer an electrical signal to the tissues that are to be stimulated. Those electrical contacts may, for instance, be situated in a paddle configured for implantation in a patient adjacent the tissue that is to be stimulated, such as along the spinal cord of a patient. SCS paddles typically have the lead wire or wires emerging from the bottom edge of the paddle, in the same plane as the body of the paddle. Also, typically there is a strain relief, molded along with the paddle, which surrounds the emerging lead or leads for approximately 5-8 mm, and beyond that the flexible leads continue onward to the power source.
Such paddle electrodes may be provided in a variety of configurations, with particular configurations being used for particular patient conditions. For instance, one patient's condition may require use of a single 8-electrode paddle, while another patient's condition may require use of multiple 6-electrode paddles. Thus, some instances may call for the use of multiple electrodes, wherein two or more leads are attached to a single implanted pulse generator. A common example of the use of multiple electrodes is the placement of two percutaneous SCS electrodes plugged into two corresponding ports on the implanted pulse generator. These electrodes are inserted independently into the implanted pulse generator, and while they may be anchored together subcutaneously, they are not coupled together at the ends where the stimulating contacts are located. Likewise, two or more paddle electrodes that are implanted for use with a single pulse generator are typically not coupled together.
When using multiple electrodes, a surgeon may suture two electrodes together to form a larger or longer array. In doing so, rather than performing two separate laminectomies at adjacent spinal levels to implant two electrodes, a single laminectomy may be performed to insert the two joined electrodes, using the lower electrode to push the upper electrode into position. Unfortunately, however, as the two electrodes remain separate elements not particularly configured for a modular assembly, this procedure can be quite difficult to perform.
Furthermore, while a large array of electrical contacts on a single electrode might likewise achieve the same result (i.e., providing a wider area of electrical stimulation from a single electrode assembly implanted through a single laminectomy), providing for all possibly desired large arrays would be cost-prohibitive, and likewise require the manufacture and maintenance of a stock of a large quantity of different electrodes. For instance, a large electrode, such as might be used as a thoracolumbar electrode, may be too large to use safely in the cervical spine. Similarly, insertion of a long electrode into the spine at any level may encounter an obstruction, calling for the use of a shorter electrode. Moreover, the larger array can use up contact positions on the implanted pulse generator (or recorder) which might otherwise be useful. For example, an intraspinal electrode might be supplemented by a subcutaneous electrode, with both electrodes connected to a single generator. Of course, such connection to a single generator would only be possible if there are unused contact positions available.
Still further, traditional electrodes may be quite difficult to manipulate during implantation. Presently available electrodes, with their irregular shapes and soft materials, are very difficult to grasp with standard surgical tools such as forceps, especially once they have been lubricated by body fluids in the surgical field. Often the surgical exposure is deep, narrow, and dark. Existing electrodes typically are not supplied with a specialized insertion tool, and attempting to manipulate them can be quite frustrating.
It would therefore be advantageous to provide an electrode that is configurable into varied electrical contact configurations so as to be selectively applicable to various patient conditions requiring electrical stimulation. It would also be advantageous to provide a tool suitable for aiding in the implantation and manipulation of such a variably configurable electrode.
SCS is just one example of the potential applications of the present invention; it also offers advantages for other implanted stimulator applications, including but not limited to motor cortex, peripheral nerve, subcutaneous, and sacral nerve roots. It is also applicable to recording from the same and additional locations in the body.